From other help page, it is advised to put use any cloth or piece of fabric, which is thick enough and cover the heatbed. This will ensure you won't damage (scratch). See here.
yes, that is for when you need to work around the bed so you do not scratch it, For this step, if you use a cloth then the distance from the probe to the bed will be off and throw off the calibration, so please do not use a cloth on the bed for this part.
See here.